Bacterial meningitis in the newborn: a prospective study of mortality and morbidity

High-risk Escherichia coli clones that cause neonatal meningitis and association with recrudescent infection

Neonatal meningitis is a devastating disease associated with high mortality and neurological sequelae. Escherichia coli is the second most common cause of neonatal meningitis in full-term infants (herein NMEC) and the most common cause of meningitis in preterm neonates. Here, we investigated the genomic relatedness of a collection of 58 NMEC isolates spanning 1974-2020 and isolated from seven different geographic regions. We show NMEC are comprised of diverse sequence types (STs), with ST95 (34.5%) and ST1193 (15.5%) the most common. No single virulence gene profile was conserved in all isolates; however, genes encoding fimbrial adhesins, iron acquisition systems, the K1 capsule, and O antigen types O18, O75, and O2 were most prevalent. Antibiotic resistance genes occurred infrequently in our collection. We also monitored the infection dynamics in three patients that suffered recrudescent invasive infection caused by the original infecting isolate despite appropriate antibiotic treatment based on antibiogram profile and resistance genotype. These patients exhibited severe gut dysbiosis. In one patient, the causative NMEC isolate was also detected in the fecal flora at the time of the second infection episode and after treatment. Thus, although antibiotics are the standard of care for NMEC treatment, our data suggest that failure to eliminate the causative NMEC that resides intestinally can lead to the existence of a refractory reservoir that may seed recrudescent infection.

Long-term impact of serious neonatal bacterial infections on neurodevelopment

BACKGROUND

Neonatal bacterial infections have long been recognized as an important cause of acute morbidity and mortality, but long-term neurodevelopmental consequences have not been comprehensively described and discussed.

OBJECTIVES

We aimed to summarize evidence on the pathogenesis, diagnosis, and epidemiology of long-term sequelae after neonatal bacterial sepsis and meningitis. We also discuss approaches for future studies to quantify the public health impact of neonatal infection-associated neurodevelopmental impairment.

SOURCES

We identified studies, both research articles and reviews, which provide mechanistic information on the long-term disease, as well as epidemiological studies that describe the frequency of neurodevelopmental impairment in children with and, for comparison, without a history of neonatal bacterial infection. Tools currently used in clinical practice and research settings to assess neurodevelopmental impairment were also reviewed.

CONTENT

We first enumerate potential direct and indirect mechanisms that can lead to brain injury following neonatal infections. We then discuss summary data, either frequencies or measures of association, from epidemiological studies. Risk factors that predict long-term outcomes are also described. Finally, we describe clinical approaches for identifying children with neurodevelopmental impairment and provide an overview of common diagnostic tools.

IMPLICATIONS

The limited number of studies that describe the long-term consequences of neonatal infections, often undertaken in high-income settings and using variable designs and diagnostic tools, are not sufficient to inform clinical practice and policy prioritization. Multi-country studies with follow-up into adolescence, standardized diagnostic approaches, and local comparator groups are needed, especially in low and middle-income countries where the incidence of neonatal sepsis is high.

Diagnostic Utility of Cerebrospinal Fluid White Blood Cell Components for the Identification of Bacterial Meningitis in Infants

BACKGROUND

To evaluate the diagnostic and predictive utility of cerebrospinal fluid (CSF) white blood cell (WBC) components in the diagnosis of bacterial meningitis in infants discharged from the neonatal intensive care unit (NICU).

METHODS

We identified a cohort of infants discharged from a Pediatrix NICU between 1997 and 2020 who did not have an immunodeficiency, had at least 1 CSF culture collected within the first 120 days of life, and at least 1 CSF laboratory specimen obtained on the day of culture collection. We only included an infant's first CSF culture and excluded cultures from CSF reservoirs and those growing contaminants or nonbacterial organisms. We examined the utility of CSF WBC components to diagnose or predict bacterial meningitis by calculating sensitivity, specificity, positive and negative predictive values, likelihood ratios, and area under the receiver operating curve (AUC) at different cutoff values for each parameter. We performed subgroup analysis excluding infants treated with antibiotics the day before CSF culture collection.

RESULTS

Of the 20 756 infants that met the study inclusion criteria, 320 (2%) were diagnosed with bacterial meningitis. We found (AUC [95% CI]) CSF WBC count (0.76 [0.73-0.79]), CSF neutrophil count (0.74 [0.70-0.78]), and CSF neutrophil percent (0.71 [0.67-0.75]) had the highest predictive values for bacterial meningitis, even when excluding infants with early antibiotic administration.

CONCLUSIONS

No single clinical prediction rule had the optimal discriminatory power for predicting culture-proven bacterial meningitis, and clinicians should be cautious when interpreting CSF WBC parameters in infants with suspected meningitis.

Mapping of conserved immunodominant epitope peptides in the outer membrane porin (Omp) L of prominent Enterobacteriaceae pathogens associated with gastrointestinal infections

BACKGROUND

Members of Enterobacteriaceae such as Escherichia coli O 157:H7, Salmonella sp., Shigella sp., Klebsiella sp., and Citrobacter freundii are responsible for the outbreak of serious foodborne illness and other mucosal infections across the globe. The outer membrane proteins (OMPs) of Enterobacteriaceae are highly immunogenic in eliciting immune responses against pathogens. Moreover, the OMPs are highly conserved in the Enterobacteriaceae family. Sequence homology in the OMPs will ensure the presence of conserved immunodominant regions with predominant epitopes. The OmpL is such an immunogen that is highly conserved among the Enterobacteriaceae pathogens. In this study, we performed computational analysis on the outer membrane porin (Omp) L of prominent Enterobacteriaceae pathogens.

RESULTS

Multiple sequence and structural alignment analysis have revealed that the OmpL protein is highly conserved among the selected Enterobacteriaceae pathogens. This amount of sequence and structural homology uncovered the conserved antibody binding B-cell epitopes in the OmpL protein. The B-cell epitopes predicted in the OmpL of Salmonella typhimurium are highly conserved among the other Enterobacteriaceae pathogens.

CONCLUSION

In conclusion, these conserved B-cell epitopes will vouch for the generation of heterologous humoral immune response in conferring cross protection against the Enterobacteriaceae pathogens and control their outbreaks across the globe.

The meningitis outbreak returns to Niger: Concern, efforts, challenges, and recommendations

Meningitis, a disease that commonly manifests in African meningitis belt, continues to be a public health problem as it is a fatal disease that leave survivors with long-term effects. Most cases of meningitis are due to bacterial and viral infection, although parasites, fungus, cancer, drugs, and immune disorders can rarely cause meningitis. Stiff neck, high temperature, light sensitivity, disorientation, headaches, and vomiting are the most typical symptoms of meningitis. Niger, being in African meningitis belt, has been affected by many meningitis outbreaks. Since 2015, a total of 20,789 cases and 1369 fatalities (CFR 6.6%) have been documented in Niger. In contrast to earlier seasons, the current outbreak of meningitis in Niger exhibits both an increase in the number of cases and a rise in the growth rate. A total of 559 cases of meningitis, including 18 fatalities (overall CFR 3.2%), were reported in the Zinder Region, southeast of Niger, from 1 November 2022 to 27 January 2023, compared to 231 cases reported from 1 November 2021 to 31 January 2022. In the current outbreak, the Neisseria meningitidis serogroup C (NmC) is responsible for the majority of laboratory confirmed cases (104/111; 93.7%). To organize the response to the outbreak, a global team of WHO and other partners, including MSF and UNICEF, has been sent to Niger. Even though there are many challenges in battle against meningitis in Niger, immunization, antibiotics administration and strong disease surveillance are recommended techniques to cope with the current meningitis outbreak in Niger.

O-Acetylation of Capsular Polysialic Acid Enables Escherichia coli K1 Escaping from Siglec-Mediated Innate Immunity and Lysosomal Degradation of E. coli-Containing Vacuoles in Macrophage-Like Cells

Escherichia coli K1 causes bacteremia and meningitis in human neonates. The K1 capsule, an α2,8-linked polysialic acid (PSA) homopolymer, is its essential virulence factor. PSA is usually partially modified by O-acetyl groups. It is known that O-acetylation alters the antigenicity of PSA, but its impact on the interactions between E. coli K1 and host cells is unclear. In this study, a phase variant was obtained by passage of E. coli K1 parent strain, which expressed a capsule with 44% O-acetylation whereas the capsule of the parent strain has only 3%. The variant strain showed significantly reduced adherence and invasion to macrophage-like cells in comparison to the parent strain. Furthermore, we found that O-acetylation of PSA enhanced the modulation of trafficking of E. coli-containing vacuoles (ECV), enabling them to avoid fusing with lysosomes in these cells. Intriguingly, by using quartz crystal microbalance, we demonstrated that the PSA purified from the parent strain interacted with human sialic acid-binding immunoglobulin-like lectins (Siglecs), including Siglec-5, Siglec-7, Siglec-11, and Siglec-14. However, O-acetylated PSA from the variant interacted much less and also suppressed the production of Siglec-mediated proinflammatory cytokines. The adherence of the parent strain to human macrophage-like cells was significantly blocked by monoclonal antibodies against Siglec-11 and Siglec-14. Furthermore, the variant strain caused increased bacteremia and higher lethality in neonatal mice compared to the parent strain. These data elucidate that O-acetylation of K1 capsule enables E. coli to escape from Siglec-mediated innate immunity and lysosomal degradation; therefore, it is a strategy used by E. coli K1 to regulate its virulence.

IMPORTANCEEscherichia coli K1 is a leading cause of neonatal meningitis. The mortality and morbidity of this disease remain significantly high despite antibiotic therapy. One major limitation on advances in prevention and therapy for meningitis is an incomplete understanding of its pathogenesis. E. coli K1 is surrounded by PSA, which is observed to have high-frequency variation of O-acetyl modification. Here, we present an in-depth study of the function of O-acetylation in PSA at each stage of host-pathogen interaction. We found that a high level of O-acetylation significantly interfered with Siglec-mediated bacterial adherence to macrophage-like cells, and blunted the proinflammatory response. Furthermore, the O-acetylation of PSA modulated the trafficking of ECVs to prevent them from fusing with lysosomes, enabling them to escape degradation by lysozymes within these cells. Elucidating how subtle modification of the capsule enhances bacterial defenses against host innate immunity will enable the future development of effective drugs or vaccines against infection by E. coli K1.

Characterization of the Blood and Cerebrospinal Fluid Microbiome in Children with Bacterial Meningitis and Its Potential Correlation with Inflammation

Bacterial meningitis shows a higher incidence in children than adults, but signs may be scarce. Although some pathogenic microorganisms of meningitis from cerebrospinal fluid (CSF) have been reported, the signature of the representative microbiota in CSF and blood samples from patients remains incompletely revealed. To extend the understanding of the microbiome in patients, we recruited 32 children with bacterial meningitis, 30 undiagnosed infectious children, and 10 matched healthy individuals, which was followed by untargeted metagenomic next-generation sequencing (mNGS) and bioinformatic analysis. Our results showed that children with bacterial meningitis exhibited different microbiome signatures in their CSF and blood compared with undiagnosed and healthy children, and patients could be divided into varied subsets according to these signatures, including Escherichia coli, Klebsiella pneumoniae, Thermothelomyces thermophila, Lactobacillus acidophilus, and Staphylococcus haemolyticus. To further explore their potential role in patients’ conditions, we examined their correlation with clinical parameters. Importantly, microbiome signatures with compositional changes were correlated with the C-reactive protein (CRP) level in blood and granulocyte percentage in CSF. Moreover, the blood in subsets of patients with a predominance of Klebsiella pneumoniae could replace CSF as the main specimen for clinical monitoring.

IMPORTANCE This study revealed the microbial compositions in children with bacterial meningitis who were treated with antibiotics and made a comprehensive comparison between blood and CSF specimens for the risk and prognosis assessment. We found that microbiome signatures could distinguish patient subsets in the children and were correlated with the CRP level in blood and granulocyte percentage in CSF. The compositional changes in representative microbiota constituents could provide guidance for clinical monitoring and antibiotic intervention.

Association of Infection in Neonates and Long-Term Neurodevelopmental Outcome

Perinatal and neonatal infection and associated inflammatory response may adversely affect brain development and lead to neurodevelopmental impairment. Factors that predict the risk of infection and subsequent adverse outcomes have been identified but substantial gaps remain in identifying mechanisms and interventions that can alter outcomes. This article describes the current epidemiology of neonatal sepsis, the pathogenesis of brain injury with sepsis, and the reported long-term neurodevelopment outcomes among survivors.

Etiology of Neonatal Bacterial Meningitis and Their Antibiotic Susceptibility Pattern at the University of Gondar Comprehensive Specialized Hospital, Ethiopia: A Seven-Year Retrospective Study

Background

Meningitis, which is mostly caused by infectious agents, occurs more commonly during the first month of life. Bacterial meningitis is an important source of mortality and morbidity, especially in neonates of resource-limited countries. We aimed to determine the prevalence and etiological agents of bacterial meningitis and their antibiotic susceptibility pattern in neonates at the University of Gondar Comprehensive Specialized Hospital.

Methods

We collected retrospective data from bacteriological results of cerebrospinal fluid of meningitis suspected neonates from 2013 to 2019. Sample collection, culture preparation, bacterial identification, and susceptibility testing were performed using standard microbiological techniques. We extracted data on socio-demographic characteristics and culture and antibiotic susceptibility testing results. We inputted the data using Epi-info version 7 and exported it to SPSS version 20 for analysis.

Results

In this study, 1101 cerebrospinal fluid samples, 595 (54%) male and 506 (46%) female neonates, were cultured to look for meningitis-causing bacteria. Of 1101 cerebrospinal fluid, 19 (1.73%) were culture positive for meningitis-causing bacteria. The common etiological agents were Klebsiella pneumoniae 36.8% (7), non-lactose-fermenter Gram-negative rods 21% (4), and Group B streptococcus 15.8% (3). The overall resistance rate among cephalosporin, cotrimoxazole, penicillin, and aminoglycosides classes were 90%, 88.9%, 77.3%, and 54.54%, respectively. Of all isolates, 58% (11) were multidrug-resistant, including all the non-lactose-fermenter Gram-negative rods and 71.4% of the Klebsiella pneumonia isolates.

Conclusion

The prevalence of neonatal bacterial meningitis was 1.73%. Klebsiella pneumonia and other Gram-negative rods, with a high multidrug-resistant rate, were the leading cause of neonatal bacterial meningitis. Further studies are needed to explore the source of infection, incidence, and risk factors of neonatal bacterial meningitis.

An improved clinical prediction rule for identifying neonatal bacterial meningitis: a multicenter cohort study

BACKGROUND

To refine the bacterial meningitis (BM) score by improving its predictability of neonatal BM.

METHODS

A multicenter, ambispective cohort study was conducted in China, comprising 9 hospitals (retrospective cohort: January 2001 to December 2017; prospective cohort: January 2018 to August 2019). Of 3,504 eligible full-term neonates, 475 neonates with cerebrospinal fluid (CSF) pleocytosis were included. Based on the receiver operating characteristic (ROC) curve and logistic regression analyses, the BM score was refined by changing the thresholds of CSF protein level and the CSF absolute neutrophil count (ANC), and removing some variables (the peripheral blood ANC and a history of seizure before or at the time of presentation).

RESULTS

Of 475 neonates, 94 (19.8%) had BM. Based on the refined BM score, neonates with none of the following high-risk predictors were classified as being at very low risk for BM: CSF protein level ≥1,650 mg/L, CSF ANC ≥84×10⁶ cells/L, and positive CSF Gram stain result. The refined score showed 100% sensitivity in identifying BM and much higher specificity compared to that for the BM score (70.9% vs. 19.4%).

CONCLUSIONS

The refined BM score effectively identifies neonatal BM, and further studies are required to confirm our findings in prospective studies.

Neonatal Escherichia coli Meningitis, Complications, and Neurological Outcome

Neonatal bacterial meningitis represents a major cause of mortality and morbidity in newborns worldwide. It leads to immediate and long-term neurological complications. In this article, we reported a case of a term newborn with an unremarkable pregnancy and delivery, who was admitted to our neonatal ward on the fifth day of life for fever. Cerebrospinal fluid culture was positive for Escherichia coli. The infant had neurological deterioration and continued fever despite adequate antibiotic therapy. Brain MRI showed multiple subdural abscesses with ventriculitis. Antibiotic therapy was maintained for 90 days with total resolution of the abscesses. The child has a normal physical examination and appropriate psychomotor development at 9 months of age.

[A clinical analysis of bacterial meningitis in full-term and preterm infants]

OBJECTIVE

To study the clinical features and prognosis of bacterial meningitis in full-term and preterm infants.

METHODS

A retrospective analysis was performed for the clinical data of 102 neonates with bacterial meningitis. According to the gestational age, they were divided into a preterm group (n=46) and a full-term group (n=56). The two groups were compared in terms of clinical manifestations, laboratory markers, imaging findings, and clinical outcomes.

RESULTS

Poor response and apnea were the major clinical manifestations in the preterm group (P<0.05), while pyrexia and convulsions were more common in the full-term group (P<0.05). The full-term group had a significantly higher glucose level in cerebrospinal fluid (CSF) than the preterm group (P<0.05). Compared with the full-term group, the preterm group had significantly higher C-reactive protein level, positive rate of blood culture, and incidence rate of poor prognosis (P<0.05). There were no significant differences between the two groups in leukocyte count in peripheral blood, levels of leukocytes and protein in CSF, and positive rate of CSF culture (P>0.05).

CONCLUSIONS

There are certain differences in the clinical manifestations between full-term and preterm infants with bacterial meningitis. Preterm infants tend to have a higher incidence rate of poor prognosis.

Epidemiology of Meningitis in Canadian Neonatal Intensive Care Units

BACKGROUND

Meningitis is a serious disease that occurs more commonly in the neonatal period than in any other age group. Recent data from large national cohorts are needed to determine if the epidemiology of neonatal meningitis (NM) has changed.

AIM

To assess the rates, causative organisms, risk factors, temporal trends and short-term outcomes of NM in Canadian Neonatal Intensive Care Units (NICUs).

METHODS

A retrospective review of newborn infants admitted to NICUs participating in the Canadian Neonatal Network between January 2010 and December 2016. Patients with meningitis were reviewed. Outcomes of patients with meningitis were compared with 1:2 matched (for gestation, sex and birth weight) neonates without meningitis.

RESULTS

Rates of NM ranged between 2.2 and 3.5/1000 NICU admissions during the 7-year study period with the majority of patients (87%) having late-onset meningitis (at >3 days after birth). The most common bacterial organism for both early- and late-onset meningitis was Escherichia coli followed by group B streptococci. Only 31% [95% confidence interval (CI): 24.06-38.63) of neonates with meningitis had simultaneous bacteremia. NM was associated with increased seizures [odds ratio (OR): 8.63; 95% CI: 4.73-15.7], retinopathy of prematurity (OR: 3.23; 95% CI: 1.30-8.02), bronchopulmonary dysplasia (OR: 1.93; 95% CI: 1.11-3.35), days of mechanical ventilation (OR: 1.03; 95% CI: 1.02-1.04) and length of hospital stay (OR: 1.02; 95% CI: 1.01-1.02), but not with mortality before discharge (OR: 1.29; 95% CI: 0.74-2.23).

CONCLUSIONS

The rate of NM remains largely unchanged in Canadian NICUs. NM was associated with increased major morbidities and longer hospital stay but not with mortality before discharge.

Brain imaging can predict neurodevelopmental outcome of Group B streptococcal meningitis in neonates

AIM

The association between cranial ultrasound (CUS) or magnetic resonance imaging (MRI) lesions and neonatal Group B streptococcal (GBS) meningitis outcome has not been studied in detail.

METHODS

This retrospective study assessed CUS, cranial MRI and neurodevelopmental outcome in 50 neonates with GBS meningitis admitted to three neonatal intensive care units in the Netherlands between 1992 and 2014. Death, cognitive outcome and motor outcome below -1 SD were considered as adverse outcomes.

RESULTS

CUS was available in all and MRIs in 31 infants (62%) with 28 CUS (56%) and 27 MRIs (87%) being abnormal. MRI lesions were multifocal (n = 10, 37%), bilateral (n = 22; 82%) and extensive (n = 11; 41%). A total of 10 died in the neonatal period. Median age at assessment was 24 months. Among survivors, abnormal cognitive outcome and motor outcome were seen in 23 and 20 patients, respectively. Abnormal CUS [odds ratio (OR) 5.3, p = 0.017], extensive bilateral deep grey lesions (OR 6.7, p = 0.035) and white matter lesions (OR 14.0, p = 0.039) correlated with abnormal motor outcome. Extensive bilateral deep grey matter lesions correlated with abnormal cognitive outcome (OR 8.1, p = 0.029).

CONCLUSION

Abnormal CUS and the most severely affected MRIs were associated with poor neurodevelopmental outcome in neonatal GBS meningitis.

Comparing Single vs. Combined Cerebrospinal Fluid Parameters for Diagnosing Full-Term Neonatal Bacterial Meningitis

Objectives: To identify and compare the cerebrospinal fluid (CSF) parameters that predict the presence of neonatal bacterial meningitis using optimal cutoff values, and to derive and compare predictive profiles based on a combination of individual parameters for the same purpose.

Study Design: The retrospective component of the Shanghai Neonate Meningitis Cohort included all term neonates who underwent lumbar puncture between 2000 and 2017. Those with severe neurological diseases, histories of ventricular drainage, or traumatic lumbar punctures were excluded. Reference ranges were determined for non-bacterial meningitis neonates based on the 5th, 25th, 50th, 75th, and 95th CSF parameter quantiles, and their relationships with age were calculated using generalized additive models that tested for linear relationships. The optimal cutoff value for each measured CSF parameter was calculated using receiver operating characteristic analysis and by deriving the Youden's index. Parameters with good diagnostic efficacies were combined to produce predictive profiles using logistic regression. The diagnostic efficacies of the single parameters and profiles were compared in neonates with confirmed bacterial meningitis.

Results: White blood cells (WBCs) in CSF showed a higher diagnostic ability for neonatal bacterial meningitis than CSF protein, glucose, lactate dehydrogenase, or chloride. The sensitivity and specificity of the diagnostic cutoff value for WBCs (20 × 10⁶/L) were 95.1 and 98.7%, respectively. Profiles based on CSF parameter combinations improved the specificities slightly to 99.0–99.7%. However, employing predictive profiles did not improve sensitivities, which remained at 95.1–96.0%.

Conclusions: Profiles for predicting neonatal bacterial meningitis improve the sensitivity and specificity of diagnosis slightly, although not appreciably, compared to the single parameter of CSF WBC alone.

Etiology and Clinical Features of Full-Term Neonatal Bacterial Meningitis: A Multicenter Retrospective Cohort Study

Objective: Neonatal bacterial meningitis is a severe infectious disease with a high risk of neurodevelopmental sequelae. The causative pathogens may be related to specific clinical features of the disease. Therefore, this study aimed at determining the pathogen-specific and clinical features of bacterial meningitis in full-term neonates. Methods: We enrolled neonates from the Shanghai Neonate Meningitis Cohort (2005-2017), which is a multicenter retrospective cohort that recruits almost all full-term neonates in Shanghai who underwent lumbar puncture. Patient history and clinical examination results were extracted from the computer-documented information systems of four hospitals. The trends of pathogen distribution were analyzed and differences in the clinical manifestations, treatment, and clinical outcomes at discharge were compared according to the causative pathogen. Logistic regression was used to evaluate the pathogen-specific risk of neurological complications. Results: In total, 518 cases of neonatal meningitis, including 189 proven cases, were included. Group B Streptococcus (GBS) and Escherichia coli (E. coli) were the leading pathogens in proven cases of early-onset and late-onset neonatal meningitis, respectively. The proportion of early-onset and late-onset GBS and late-onset E. coli meningitis cases increased gradually. GBS meningitis had the highest risk of neurological complications, whereas the overall incidence of hydrocephalus and brain abscess in E. coli was higher than that in GBS. Conclusions: Rates of neonatal GBS and E. coli meningitis were high in 2005-2017 in Shanghai, and the risk of neurological complications was also high. Therefore, active prevention, rational use of antibiotics, and continuous monitoring of GBS and E. coli in neonates should be initiated in Shanghai.

Predictors of Poor Outcome in Neonates with Pyogenic Meningitis in a Level-Three Neonatal Intensive Care Unit of Developing Country

BACKGROUND

The mortality of neonatal pyogenic meningitis is reduced to 10-15%, but morbidity is unchanged.

METHODS

Primary objective is to determine the outcome, i.e. death or abnormal neurological examination (NE) at discharge and abnormal developmental quotient (DQ) at 3 months. Secondary objective is to find predictors of poor outcome.

RESULTS

In all, 89 neonates enrolled, 10 expired and 24 neonates had abnormal NE at discharge. A total of 59 neonates came for follow up, 13 had DQ < 70. Prolonged shock (odds ratio, OR: 8.28; p = 0.001), coma (OR: 4.3; p = 0.001), seizures (OR: 14; p = 0.012), mechanical ventilation (OR: 18.55; p = 0.00), orogastric feeding (OR: 2.78; p = 0.042) and electroencephalography (EEG; OR: 9.6; p = 0.00) predicted poor short-term outcome. Abnormal NE at discharge (OR: 15.6; p = 0.001), EEG (OR = 10.60; p = 0.00) and brainstem-evoked reflex audiometry (OR = 37.20, p = 0.00) predicted a low DQ at 3 months. Mortality and morbidity of neonates with Pyogenic Meningitis (PM) were similar to that in developed countries. Outcome depended on severity of the disease and NE at discharge.

Granulocyte Colony-Stimulating Factor Alleviates Bacterial-Induced Neuronal Apoptotic Damage in the Neonatal Rat Brain through Epigenetic Histone Modification

Bacterial meningitis during the perinatal period may cause long-term neurological deficits. The study investigated whether bacterial lipopolysaccharide (LPS) derived from E. coli. led to neuronal apoptosis with an impaired performance of long-term cognitive function involving the activation of histone modification in the TNF-α gene promoter. Further, we looked into the therapeutic efficacy of granulocyte colony-stimulating factor (G-CSF) in a neonatal brain suffering from perinatal bacterial meningitis. We applied the following research techniques: neurobehavioral tasks, confocal laser microscopy, chromatin immunoprecipitation, and Western blotting. At postnatal day 10, the animals were subjected to LPS and/or G-CSF. The target brain tissues were then collected at P17. Some animals (P45) were studied using neurobehavioral tasks. The LPS-injected group revealed significantly increased expression of NF-κB phosphorylation and trimethylated H3K4 in the TNFA gene promoter locus. Furthermore, the caspase-3, neuronal apoptosis expression, and an impaired performance in cognitive functions were also found in our study. Such deleterious outcomes described above were markedly alleviated by G-CSF therapy. This study suggests that selective therapeutic action sites of G-CSF through epigenetic regulation in the TNFA gene promoter locus may exert a potentially beneficial role for the neonatal brain suffering from perinatal bacterial-induced meningitis.

Non-invasive three-dimensional imaging of Escherichia coli K1 infection using diffuse light imaging tomography combined with micro-computed tomography

In contrast to two-dimensional bioluminescence imaging, three dimensional diffuse light imaging tomography with integrated micro-computed tomography (DLIT-μCT) has the potential to realise spatial variations in infection patterns when imaging experimental animals dosed with derivatives of virulent bacteria carrying bioluminescent reporter genes such as the lux operon from the bacterium Photorhabdus luminescens. The method provides an opportunity to precisely localise the bacterial infection sites within the animal and enables the generation of four-dimensional movies of the infection cycle. Here, we describe the use of the PerkinElmer IVIS SpectrumCT in vivo imaging system to investigate progression of lethal systemic infection in neonatal rats following colonisation of the gastrointestinal tract with the neonatal pathogen Escherichia coli K1. We confirm previous observations that these bacteria stably colonize the colon and small intestine following feeding of the infectious dose from a micropipette; invading bacteria migrate across the gut epithelium into the blood circulation and establish foci of infection in major organs, including the brain. DLIT-μCT revealed novel multiple sites of colonisation within the alimentary canal, including the tongue, oesophagus and stomach, with penetration of the non-keratinised oesophageal epithelial surface, providing strong evidence of a further major site for bacterial dissemination. We highlight technical issues associated with imaging of infections in new born rat pups and show that the whole-body and organ bioburden correlates with disease severity.

Pathoadaptive Mutations of Escherichia coli K1 in Experimental Neonatal Systemic Infection

Although Escherichia coli K1 strains are benign commensals in adults, their acquisition at birth by the newborn may result in life-threatening systemic infections, most commonly sepsis and meningitis. Key features of these infections, including stable gastrointestinal (GI) colonization and age-dependent invasion of the bloodstream, can be replicated in the neonatal rat. We previously increased the capacity of a septicemia isolate of E. coli K1 to elicit systemic infection following colonization of the small intestine by serial passage through two-day-old (P2) rat pups. The passaged strain, A192PP (belonging to sequence type 95), induces lethal infection in all pups fed 2–6 x 10⁶ CFU. Here we use whole-genome sequencing to identify mutations responsible for the threefold increase in lethality between the initial clinical isolate and the passaged derivative. Only four single nucleotide polymorphisms (SNPs), in genes (gloB, yjgV, tdcE) or promoters (thrA) involved in metabolic functions, were found: no changes were detected in genes encoding virulence determinants associated with the invasive potential of E. coli K1. The passaged strain differed in carbon source utilization in comparison to the clinical isolate, most notably its inability to metabolize glucose for growth. Deletion of each of the four genes from the E. coli A192PP chromosome altered the proteome, reduced the number of colonizing bacteria in the small intestine and increased the number of P2 survivors. This work indicates that changes in metabolic potential lead to increased colonization of the neonatal GI tract, increasing the potential for translocation across the GI epithelium into the systemic circulation.

Neonatal bacterial meningitis in Tikur Anbessa Specialized Hospital, Ethiopia: a 10-year retrospective review

BACKGROUND

Bacterial meningitis is still a major public health threat in developing countries. It is an overwhelming infection with a high morbidity and mortality rate, especially in neonates. The aim of this study was to determine the prevalence and etiological agents that cause bacterial neonatal meningitis at Tikur Anbessa Specialized Hospital (TASH).

METHODS

This is a retrospective analysis of 1189 cerebrospinal fluid (CSF) specimens submitted to the bacteriology laboratory of TASH for culture from 2001 to 2010. All newborns younger than 29 days old that were suspected for bacterial meningitis cases were included in the study.

RESULTS

Based on CSF culture, 56 newborns were identified as having bacterial meningitis from a total of 1189 suspected cases. The overall prevalence of neonatal bacterial meningitis from the total suspected cases was 4.7%. The organisms identified and their prevalence rates were Streptococcus pneumoniae 13 (23%), Escherichia coli 9 (16%), Acinetobacter 7 (13%), Neisseria meningitides 5 (9%), Klebsiella spp. 5 (9%), Staphylococcus aureus 3 (5%) and Streptococcus pyogen 3 (5%). There were two (4%) cases each that was caused by Coagulase-Negative-Staphylococcus and Non-Group-A-Streptococcus, while 1 (2%) caused by Haemophilus influenzae. S. pneumoniae was the main etiological agent identified from CSF culture. The male to female ratio was 1:0.88 (53% were male). The birth weights of 34 (61%) patients were under 2500 g, and 22 (39%) patients had normal birth weights. Twenty-seven (48%) were early onset cases, and 29 (52%) were late-onset.

CONCLUSION

Streptococcus pneumoniae and Escherichia coli were the two main etiological agents for neonatal bacterial meningitis infection in the study area.

Pancytopenia due to linezolid treatment

Antibiotic-resistant infections constitute a significant portion of severe childhood infections. A gradually increasing resistance and treatment difficulty are observed in infections caused by enterococci, staphylococci and pneumococci. Linezolid is one of the new antibiotics which has recently been introduced for clinical use with gram positive efficiency. In this article, a pediatric patient with vancomycin-resistant enterococcus infection who developed reversible bone marrow supression related with use of linesolid was presented. A shunt was inserted in a ten-month old female patient who had been operated at the age of one month because of meningomyelocele and who had developed hydrocephalus. Linezolid and meropenem treatment was started when vancomycin-resistant Enterococcus faecium and extended-spectrum beta-lactamase positive Escherichia coli grew in cerebrospinal fluid culture. In the second week of treatment, cerebrospinal fluid findings improved. However, bone marrow supression was observed. Linezolid treatment was discontinued. In the follow-up, the blood cell counts returned to normal levels.

Adjuvant corticosteroids for reducing death in neonatal bacterial meningitis

BACKGROUND

Bacterial meningitis remains a significant cause of neonatal and childhood morbidity and mortality in many countries of the world, particularly in developing countries. In some instances, children recover but remain impaired as a result of neurological sequelae such as hearing loss, developmental delay and cognitive impairment.

OBJECTIVES

To assess the effectiveness and safety of adjunctive corticosteroids in reducing death and neurological sequelae in neonates with bacterial meningitis.

SEARCH METHODS

We searched the Cochrane Central Register of Controlled Trials (CENTRAL; 2015, Issue 7), MEDLINE via PubMed (1966 to July 2015), African Index Medicus (up to January 2015), the Cumulative Index to Nursing and Allied Health Literature (CINAHL) (up to July 2015), EMBASE (up to July 2015) and the metaRegister of Controlled Trials (mRCT) for ongoing trials.

SELECTION CRITERIA

All randomised controlled trials (RCTs) or quasi-RCTs of adjunctive corticosteroids for treatment of neonates with bacterial meningitis.

DATA COLLECTION AND ANALYSIS

Two review authors independently assessed and extracted data on methods, participants, interventions and outcomes (all-cause death until hospital discharge, presence of sensorineural deafness at one year and presence of neurological deficits or developmental delay at two years, adverse events). Risk ratio (RR), risk difference (RD) and number needed to treat for an additional beneficial outcome (NNTB) or number needed to treat for an additional harmful outcome (NNTH) were calculated when appropriate. We assessed quality using the Cochrane risk of bias assessment tool and the GRADE (Grades of Recommendation, Assessment, Development and Evaluation) system.

MAIN RESULTS

We found two trials with 132 participants that met our inclusion criteria. One of the included trials was a quasi-randomised trial.Adjunctive corticosteroids reduced the risk of death (typical RR 0.46, 95% confidence interval (CI) 0.24 to 0.88; typical RD -0.19, 95% CI -0.33 to -0.04; NNTB = 6; two studies, 132 participants, very low-quality evidence) but did not have a significant effect on the number of infants with sensorineural deafness at two years (RR 1.80, 95% CI 0.18 to 18.21; RD 0.04, 95% CI -0.12 to 0.21; one study, 38 participants, low-quality evidence). In one trial, dexamethasone reduced the likelihood of hearing loss at four to 10 weeks post discharge (RR 0.41, 95% CI 0.17 to 0.98; RD -0.25, 95% CI -0.48 to -0.01; one study, 59 participants, low-quality evidence). Data reported on the other outcomes of interest were insufficient.

AUTHORS' CONCLUSIONS

Very low-quality data from two randomised controlled trials suggest that some reduction in death and hearing loss may result from use of adjunctive steroids alongside standard antibiotic therapy for treatment of patients with neonatal meningitis. Benefit is not yet seen with regards to reduction in neurological sequelae. Researchers who wish to clarify these findings must conduct more robustly designed trials with greater numbers of participants, evaluating more relevant outcomes and providing adequate follow-up.

Neonatal purulent meningitis in southern Tunisia: Epidemiology, bacteriology, risk factors and prognosis

OBJECTIVES

To study the epidemiological, clinical and bacteriological aspects and outcome of purulent neonatal meningitis (PNM).

METHODOLOGY

Retrospective analysis of 55 cases of PNM hospitalized in the pediatric ward of Hedi Chaker Hospital from 1990 to 2012. Infants less than 29 days of age were included. The diagnosis was made on either the presence of bacteria in the cerebrospinal fluid (CSF) or the combination of pleocytosis >30 cells/mm(3), protein level >1.3 g/l and glucose level <2.2 mmol/l or CSF/blood glucose ratio <0.4.

RESULTS

The male:female sex ratio was 1.75. One or more maternal risk factors for infection were found in 24 cases. The main symptoms were fever and poor feeding. Soluble antigen was positive in four cases and cultures had isolated the bacteria in 28 cases. The mortality rate was 40%. The sequelae rate in the survivors was 16.4%.

CONCLUSION

This study emphasizes the severity of PNM with high rates of mortality and neurological sequelae.

A population-based prospective birth cohort study of childhood neurocognitive and psychological functioning in healthy survivors of early life meningitis

PURPOSE

To determine neurocognitive, educational, and psychological functioning during childhood and early adolescence among survivors of early life meningitis who are apparently healthy.

METHODS

In the general population-based Avon Longitudinal Study of Parents and Children birth cohort, meningitis exposure was determined at age of 18 months. The outcomes of intelligence quotient, short-term memory, working memory, reading and spelling abilities, psychological and behavioral problems, depressive and anxiety symptoms, and psychotic experiences at ages 9 to 13 years were compared between those exposed and unexposed to meningitis. Individuals with special educational needs were excluded.

RESULTS

By age of 18 months, 67 of 11,035 children were reported to have suffered from meningitis (0.61%). These children, compared with the unexposed, performed worse on all neurocognitive and educational measures; mean difference in total intelligence quotient 7.36 (95% confidence interval, 1.60-13.11). Meningitis was associated with higher depressive and anxiety symptoms (P = .02), psychological and behavioral problems (P = .09), and increased risk of psychotic experiences; risk ratio 2.22 (95% confidence interval, 1.12-4.38).

CONCLUSIONS

Exposure to meningitis in the early life is associated with neurocognitive, educational, and psychological difficulties during childhood and early adolescence among survivors who are apparently healthy. Therefore, focusing only on serious neurologic disabilities may underestimate the true impact of early life meningitis.

Non-invasive model of neuropathogenic Escherichia coli infection in the neonatal rat

Investigation of the interactions between animal host and bacterial pathogen is only meaningful if the infection model employed replicates the principal features of the natural infection. This protocol describes procedures for the establishment and evaluation of systemic infection due to neuropathogenic Escherichia coli K1 in the neonatal rat. Colonization of the gastrointestinal tract leads to dissemination of the pathogen along the gut-lymph-blood-brain course of infection and the model displays strong age dependency. A strain of E. coli O18:K1 with enhanced virulence for the neonatal rat produces exceptionally high rates of colonization, translocation to the blood compartment and invasion of the meninges following transit through the choroid plexus. As in the human host, penetration of the central nervous system is accompanied by local inflammation and an invariably lethal outcome. The model is of proven utility for studies of the mechanism of pathogenesis, for evaluation of therapeutic interventions and for assessment of bacterial virulence.

Predictors of positive cerebrospinal fluid cultures in infants with bacteremia

BACKGROUND

Meningitis causes substantial morbidity and mortality in hospitalized infants. There is no consensus on the ability of blood cultures to predict results from cerebrospinal fluid (CSF) cultures in hospitalized infants.

METHODS

We used the Pediatrix Medical Group database of infants discharged from 333 neonatal intensive care units between 1997 and 2011. We identified all infants with a positive blood culture and a CSF culture obtained within 3 days. We evaluated the odds of a concordant blood-CSF culture pair, controlling for severity of illness, organism type, gestational age, day of blood culture and blood-CSF culture pairing, exposure to CSF-penetrating antibiotics and the presence of a ventriculo-peritoneal shunt.

RESULTS

We identified 8839 infants with 9408 blood-CSF culture pairs. Serratia marcescens (24/227, 11%) and Streptococcus pneumoniae (7/64, 11%) had the highest proportion of concordant blood-CSF culture pairs. The presence of a ventriculo-peritoneal shunt, as well as timing of the CSF culture on the same day as the blood culture, were associated with increased odds of blood-CSF culture pair concordance-odds ratio = 3.87 (95% confidence interval; 2.59-5.78) and 6.11 (2.81-13.24), respectively.

CONCLUSION

The frequency of blood-CSF culture pair concordance is related to organism type and to the timing of the CSF culture in relation to the blood culture.

Evolving trends of neonatal and childhood bacterial meningitis in northern Taiwan

BACKGROUND

The epidemiology of bacterial meningitis varies in different areas, age groups, and times. To know the trend of neonatal and childhood bacterial meningitis in northern Taiwan, we performed this 29-year-long assessment.

METHODS

Eligible patients were aged 18 years or younger, hospitalized in Mackay Memorial Hospital between 1984 and 2012, and proven by positive cerebrospinal fluid bacterial cultures. Analysis included the patient numbers and pathogens in different age groups, periods, complications, and outcomes.

RESULTS

Males were predominant in all the age groups through the years. Almost half of the patients were in the neonatal period. Patient numbers went up in the early study period and declined after 1993-1997. Group B Streptococcus and Escherichia coli were the most common pathogens in neonates, whereas in childhood were Streptococcus pneumoniae and Haemophilus influenzae type b (Hib). Patient numbers of Group B Streptococcus, S. pneumoniae, and Hib meningitis declined in the late study period, but E. coli meningitis increased. The mortality rate decreased but sequela rate increased. Among the four most common pathogens, S. pneumoniae had the worst outcome and had highest mortality rate. All Hib meningitis patients survived, but their sequela rate was the highest.

CONCLUSION

This study provides an epidemiological data on trends of neonatal and childhood bacterial meningitis in northern Taiwan during the past 29 years, including male and neonatal predominance, decrease of total patient number in recent years, change of major pathogens, and declined mortality but raised morbidity.

Altered innate defenses in the neonatal gastrointestinal tract in response to colonization by neuropathogenic Escherichia coli

Two-day-old (P2), but not 9-day-old (P9), rat pups are susceptible to systemic infection following gastrointestinal colonization by Escherichia coli K1. Age dependency reflects the capacity of colonizing K1 to translocate from gastrointestinal (GI) tract to blood. A complex GI microbiota developed by P2, showed little variation over P2 to P9, and did not prevent stable K1 colonization. Substantial developmental expression was observed over P2 to P9, including upregulation of genes encoding components of the small intestinal (α-defensins Defa24 and Defa-rs1) and colonic (trefoil factor Tff2) mucus barrier. K1 colonization modulated expression of these peptides: developmental expression of Tff2 was dysregulated in P2 tissues and was accompanied by a decrease in mucin Muc2. Conversely, α-defensin genes were upregulated in P9 tissues. We propose that incomplete development of the mucus barrier during early neonatal life and the capacity of colonizing K1 to interfere with mucus barrier maturation provide opportunities for neuropathogen translocation into the bloodstream.

High mortality among patients with bacterial meningitis in a rural hospital in Tanzania

Although the disease is an important cause of mortality in the region, most published reports on bacterial meningitis in East Africa are from urban referral hospitals. Poor laboratory facilities make diagnosis difficult in the area and treatment is limited to inexpensive antibiotics. The case-fatality 'rate' in one rural hospital in Tanzania, the Ndala Mission Hospital (NMH), appears to have increased dramatically over recent years, perhaps as the result of increasing resistance to ampicillin and chloramphenicol. The aim of the present study, which was partially retrospective and partially prospective, was to review the number, characteristics and outcome of children admitted to this hospital with bacterial meningitis and to investigate possible resistance of the causative micro-organisms to the antibiotics used. Data from the 181 children who were admitted with bacterial meningitis [confirmed by the examination of Gram-stained smears of cerebrospinal fluid (CSF)] between 1999 and 2002 were retrospectively reviewed. The overall mortality among these children was 51%. No seasonal pattern was observed in the number of cases. In a 2-month prospective study in 2002, CSF samples from 19 consecutive cases were collected in Trans-Isolate medium and shipped to the Academic Medical Center in Amsterdam for culture and analysis of antibiotic susceptibility. For only eight (42%) of the cases was there agreement between the species of bacterium identified, by Gram-staining, in Tanzania and that identified, by culture, in The Netherlands. As there was no evidence of resistance to ampicillin and the antibiotics used in the NMH were found to be of good quality, the cause of the high mortality in the NMH remains uncertain. Poor laboratory testing, long doctor-patient delays and/or poor drug administration on the wards may all be contributory factors. Attempts will now be made to address each of these problems.

Intraventricular antibiotics for bacterial meningitis in neonates

BACKGROUND

Neonatal meningitis may be caused by bacteria, especially gram-negative bacteria, which are difficult to eradicate from the cerebrospinal fluid (CSF) using safe doses of antibiotics. In theory, intraventricular administration of antibiotics would produce higher antibiotic concentrations in the CSF than intravenous administration alone, and eliminate the bacteria more quickly. However, ventricular taps may cause harm.

OBJECTIVES

To assess the effectiveness and safety of intraventricular antibiotics (with or without intravenous antibiotics) in neonates with meningitis (with or without ventriculitis) as compared to treatment with intravenous antibiotics alone.

SEARCH METHODS

The Cochrane Library, Issue 2, 2007; MEDLINE; EMBASE; CINAHL and Science Citation Index were searched in June 2007. The Oxford Database of Perinatal Trials was searched in June 2004. Pediatric Research (abstracts of proceedings) were searched (1990 to April 2007) as were reference lists of identified trials and personal files. No language restrictions were applied.This search was updated in May 2011.

SELECTION CRITERIA

Selection criteria for study inclusion were: randomised or quasi-randomised controlled trials in which intraventricular antibiotics with or without intravenous antibiotics were compared with intravenous antibiotics alone in neonates (< 28 days old) with meningitis. One of the following outcomes was required to be reported: mortality during initial hospitalisation; neonatal or infant mortality, or both; neurodevelopmental outcome; duration of hospitalisation; duration of culture positivity of CSF and side effects.

DATA COLLECTION AND ANALYSIS

All review authors abstracted information for outcomes reported and one review author checked for discrepancies and entered data into RevMan 5.1. Risk ratio (RR), risk difference (RD), number needed to treat for an additional beneficial outcome (NNTB) or number needed to treat for an additional harmful outcome (NNTH), and mean difference (MD), using the fixed-effect model are reported with 95% confidence intervals (CI).

MAIN RESULTS

The updated search in June 2011 did not identify any new trials. One study is included in the review. This study assessed the effect of intraventricular gentamicin in a mixed population of neonates (69%) and older infants (31%) with gram-negative meningitis and ventriculitis. Mortality was statistically significantly higher in the group that received intraventricular gentamicin in addition to intravenous antibiotics compared to the group receiving intravenous antibiotics alone (RR 3.43; 95% CI 1.09 to 10.74; RD 0.30; 95% CI 0.08 to 0.53); NNTH 3; 95% CI 2 to 13). Duration of CSF culture positivity did not differ significantly (MD -1.20 days; 95% CI -2.67 to 0.27).

AUTHORS' CONCLUSIONS

In one trial that enrolled infants with gram-negative meningitis and ventriculitis, the use of intraventricular antibiotics in addition to intravenous antibiotics resulted in a three-fold increased RR for mortality compared to standard treatment with intravenous antibiotics alone. Based on this result, intraventricular antibiotics as tested in this trial should be avoided. Further trials comparing these interventions are not justified in this population.

Comparison of cerebrospinal fluid in newborns and in infants ≤ 2 months old with or without meningitis

BACKGROUND

The aim of the present study was to evaluate the characteristics and accuracy of cerebrospinal fluid (CSF) parameters for neonatal meningitis, by comparing CSF data in newborns and in infants ≤ 2 months of age, with or without meningitis.

METHODS

This case-control study was performed on 120 newborns and infants ≤ 2 months old. 60 patients with meningitis were considered as the case group and 60 ill patients without meningitis were defined as the control group. Each of the two groups was divided into 0-1 months and 1-2 months old. CSF characteristics were compared in newborns in the case and control groups; in infants ≤ 2 months old in the case and control groups; and in healthy newborns and healthy infants ≤ 2 months old.

RESULTS

The mortality rate was 16.7% in the case group. The differences of CSF parameters in the case and control groups were mostly not significant, except for CSF glucose only in term newborns <7 days old (P= 0.04), and white cell count (WBC) only in 0-7-day-old term and preterm neonates (P= 0.04 and P= 0.01, respectively). Polymorphonuclear leukocyte (PMNL) level in the case group was significantly higher than in the control group (P= 0.02). CSF characteristics in healthy newborns were nearly the same as in healthy infants ≤ 2 months old. Prevalence of positive CSF culture was 31.7% in the case group. The most common pathogen was Neisseria meningitidis in the two age groups. The concomitant positive blood culture in the case group was 26.3%.

CONCLUSION

In the case of meningitis with negative CSF culture and Gram stain, diagnosis can be made on CSF parameters, clinical and laboratory findings and suspicion of meningitis. Therefore, a clinical prediction rule to classify risk for bacterial meningitis on evaluation of CSF parameters in any region should be established. More regional trials are needed to enhance the probability of diagnosis according to CSF parameters.

Epigenetic regulation of the nitrosative stress response and intracellular macrophage survival by extraintestinal pathogenic Escherichia coli

Extraintestinal pathogenic Escherichia coli (ExPEC) reside in the enteric tract as a commensal reservoir, but can transition to a pathogenic state by invading normally sterile niches, establishing infection and disseminating to invasive sites like the bloodstream. Macrophages are required for ExPEC dissemination, suggesting the pathogen has developed mechanisms to persist within professional phagocytes. Here, we report that FimX, an ExPEC-associated DNA invertase that regulates the major virulence factor type 1 pili (T1P), is also an epigenetic regulator of a LuxR-like response regulator HyxR. FimX regulated hyxR expression through bidirectional phase inversion of its promoter region at sites different from the type 1 pili promoter and independent of integration host factor (IHF). In vitro, transition from high to low HyxR expression produced enhanced tolerance of reactive nitrogen intermediates (RNIs), primarily through de-repression of hmpA, encoding a nitric oxide-detoxifying flavohaemoglobin. However, in the macrophage, HyxR produced large effects on intracellular survival in the presence and absence of RNI and independent of Hmp. Collectively, we have shown that the ability of ExPEC to survive in macrophages is contingent upon the proper transition from high to low HyxR expression through epigenetic regulatory control by FimX.

Acute bacterial meningitis in infants and children: epidemiology and management

Acute bacterial meningitis (ABM) continues to be associated with high mortality and morbidity, despite advances in antimicrobial therapy. The causative organism varies with age, immune function, immunization status, and geographic region, and empiric therapy for meningitis is based on these factors. Haemophilus influenzae type b (Hib), Streptococcus pneumoniae, and Neisseria meningitidis cause the majority of cases of ABM. Disease epidemiology is changing rapidly due to immunization practices and changing bacterial resistance patterns. Hib was the leading cause of meningitis in children prior to the introduction of an effective vaccination. In those countries where Hib vaccine is a part of the routine infant immunization schedule, Hib has now been virtually eradicated as a cause of childhood meningitis. Vaccines have also been introduced for pneumococcal and meningococcal diseases, which have significantly changed the disease profile. Where routine pneumococcal immunization has been introduced there has been a reported increase in invasive pneumococcal disease due to non-vaccine serotypes. In those parts of the world that have introduced conjugate meningococcal vaccines, there has been a significant change in the epidemiology of meningococcal meningitis. As a part of the United Nations Millennium Development Goal 4, the WHO has introduced a new vaccine policy to improve vaccine availability in resource poor countries. In addition, antibiotic resistance is an increasing problem, especially with pneumococcal infection. Effective treatment focuses on early recognition and use of effective antibiotics. This review will attempt to focus on the changing epidemiology of ABM in pediatric patients due to vaccination, the changing patterns of infecting bacterial serotypes due to vaccination, and on antibiotic resistance and its impact on current management strategies.

Oxidative stress, cytokine/chemokine and disruption of blood-brain barrier in neonate rats after meningitis by Streptococcus agalactiae

We verify the levels of cytokine/chemokine, myeloperoxidase activity, oxidative stress and disruption of BBB in hippocampus and cortex of the neonate Wistar rats after meningitis by S. agalactiae. In the hippocampus the levels were increased of CINC-1 at 6 h and 12 h, IL-1β at 6, 12 and 24 h, IL-6 at 6, 24 and 96 h, IL-10 at 24, 48 and 96 h and TNF-α at 24 h and 96 h. In the cortex the CINC-1 and IL-1β levels were found increased at 6 h. The MPO activity was significantly elevated at 24, 48 and 98 h in hippocampus and at 6, 12, 24, 48 and 96 h in the cortex. The breakdown of BBB started at 12 h.TBARS levels were elevated in the hippocampus at 6, 12, 24, 48, 72 and 96 h and cortex at 72 and 96 h. Protein carbonyls were elevated in the hippocampus and cortex at 6, 24, 48, 72 and 96 h. There was a decrease of SOD activity in hippocampus and in cortex. Catalase activity was elevated in hippocampus at 6 h and in the cortex at 12 and 96 h. Neonatal bacterial infections of the CNS are severe, the interference with the complex network of cytokines/chemokine, other inflammatory mediators and oxidants tend to aggravate the illness and can be involved in the breakdown of the BBB.

Functional and structural characterization of polysaccharide co-polymerase proteins required for polymer export in ATP-binding cassette transporter-dependent capsule biosynthesis pathways

Neisseria meningitidis serogroup B and Escherichia coli K1 bacteria produce a capsular polysaccharide (CPS) that is composed of α2,8-linked polysialic acid (PSA). Biosynthesis of PSA in these bacteria occurs via an ABC (ATP-binding cassette) transporter-dependent pathway. In N. meningitidis, export of PSA to the surface of the bacterium requires two proteins that form an ABC transporter (CtrC and CtrD) and two additional proteins, CtrA and CtrB, that are proposed to form a cell envelope-spanning export complex. CtrA is a member of the outer membrane polysaccharide export (OPX) family of proteins, which are proposed to form a pore to mediate export of CPSs across the outer membrane. CtrB is an inner membrane protein belonging to the polysaccharide co-polymerase (PCP) family. PCP proteins involved in other bacterial polysaccharide assembly systems form structures that extend into the periplasm from the inner membrane. There is currently no structural information available for PCP or OPX proteins involved in an ABC transporter-dependent CPS biosynthesis pathway to support their proposed roles in polysaccharide export. Here, we report cryo-EM images of purified CtrB reconstituted into lipid bilayers. These images contained molecular top and side views of CtrB and showed that it formed a conical oligomer that extended ∼125 Å from the membrane. This structure is consistent with CtrB functioning as a component of an envelope-spanning complex. Cross-complementation of CtrA and CtrB in E. coli mutants with defects in genes encoding the corresponding PCP and OPX proteins show that PCP-OPX pairs require interactions with their cognate partners to export polysaccharide. These experiments add further support for the model of an ABC transporter-PCP-OPX multiprotein complex that functions to export CPS across the cell envelope.

Systematic review: neonatal meningitis in the developing world

Meningitis is more common in the neonatal period than any other time in life and is an important cause of morbidity and mortality globally. Despite the majority of the burden occurring in the developing world, the majority of the existing literature originates from wealthy countries. Mortality from neonatal meningitis in developing countries is estimated to be 40-58%, against 10% in developed countries. Important differences exist in the spectrum of pathogens isolated from cerebrospinal fluid cultures in developed versus developing countries. Briefly, while studies in developed countries have generally found Group B streptococcus (GBS), Escherichia coli and Listeria monocytogenes as important organisms, we describe how in the developing world results have varied; particularly regarding GBS, other Gram negatives (excluding E. coli), Listeria and Gram-positive organisms. The choice of empiric antibiotics should take into consideration local epidemiology if known, early versus late disease, resistance patterns and availability within resource constraints. Gaps in knowledge, the role of adjuvant therapies and future directions for research are explored.

Meningitis in neonates: bench to bedside

The clinical outcome of central nervous system infection is determined by the characteristics of the pathogen and the brain's response to the invading bacteria. How infection leads to brain injury remains unresolved. An impediment to progress is the complexity of pathophysiologic processes. Some of the mechanisms involved have been identified in experimental models, providing insights into the molecular basis of brain injury and regeneration, and hinting at targets for therapy. Adjuvant therapies have been proposed. Interventions that protect the brain are evaluated for their potential to preserve neuro-integrative functions in long-term survivors of bacterial meningitis. This article summarizes current studies evaluating pharmacologic interventions in experimental models of bacterial meningitis and discusses how the knowledge gathered could translate into more effective therapies.

Administration of capsule-selective endosialidase E minimizes upregulation of organ gene expression induced by experimental systemic infection with Escherichia coli K1

Many neurotropic strains of Escherichia coli cause potentially lethal bacteraemia and meningitis in newborn infants by virtue of their capacity to elaborate the protective polysialic acid (polySia) K1 capsule. Recombinant capsule depolymerase, endosialidase E (endoE), selectively removes polySia from the bacterial surface; when administered intraperitoneally to infected neonatal rats, the enzyme interrupts the transit of E. coli K1 from gut to brain via the blood circulation and prevents death from systemic infection. We now show that experimental E. coli K1 infection is accompanied by extensive modulation of host gene expression in the liver, spleen and brain tissues of neonatal rats. Bacterial invasion of the brain resulted in a threefold or greater upregulation of approximately 400 genes, a large number of which were associated with the induction of inflammation and the immune and stress responses: these included genes encoding C-X-C and C-C chemokines, lipocalins, cytokines, apolipoproteins and enzymes involved in the synthesis of low-molecular-mass inflammatory mediators. Administration of a single dose of endoE, 24 h after initiation of systemic infection, markedly reduced, but did not completely abrogate, these changes in gene expression, suggesting that attenuation of E. coli K1 virulence by removal of the polySia capsule may minimize the attendant inflammatory processes that contribute to poor outcome in these severe systemic infections.

[Clinical outcome and bacterial characteristics of 99 Escherichia coli meningitis in young infants]

OBJECTIVE

To conduct a descriptive analysis of clinical, biological and prognostic aspects of Escherichia coli meningitis in young infants.

METHODS

Clinical and biological data on young infants diagnosed with neonatal E. coli meningitis (NECM) between 1988 and 2004 were collected retrospectively and analyzed with respect to the isolates'phenotypic and genotypic characteristics. The molecular analyses focused on the phylogenetic group, the sequence-O-type, and genetic virulence traits. The virulence of lethal strains was tested in a newborn rat meningitis model.

RESULTS

The median age of the 99 children analyzed was 10 days (0 to 90 days), and 83 of the patients were newborns. Thirty-three children were premature. Hyper- or hypothermia was the most frequent clinical sign at admission. Intercurrent urinary tract infection was present in 28% of cases, all over 6 days of age. 81% of blood cultures were positive. The CSF cytology was abnormal in 97% of cases. Twelve hours after admission, 34% of infants were transferred to intensive care. One-third of transfontanellar ultrasound scans done on admission were abnormal. CSH sterilization was slow in 15 % of cases, despite appropriate antibiotic therapy. The use of ciprofloxacin was associated with more rapid CSF sterilization (94 % vs 77 %, p=0.03). Six children relapsed. The average follow-up was eight months, and 21 % of children had sequelae. The case lethality rate was 14%. Fatal outcome was associated with signs of septic shock (57% vs 3%, p<10(-4)) and neurological failure (76% vs 19%, p<10(-4)) within the first 24 hours, and with abnormalities on the first ultrasound scan (63% vs 27%, p=0.03). The risk of death was higher among children infected by strains belonging to unusual sequence-O-types (50% vs 18%, p=0.01), which harbored fewer virulence factors (4.8 vs 5.9, p<10(-4)). Only aerobactin was less frequent in lethal strains (71 % vs 94%, p=0.02). Strains belonging to unusual sequence-O-types and that were lethal in the animal model induced a significantly lower level of bacteremia than strains belonging to frequent sequence-O-types (p<0.001).

CONCLUSION

E. coli meningitis remains highly lethal in infants. Clinical and molecular analyses showed a link between lethality and infrequent sequence-O-types. The avirulence of these strains in animal models suggests that fatal outcome could be due to host susceptibility more than to strain virulence.

Differential expression of the polysialyl capsule during blood-to-brain transit of neuropathogenic Escherichia coli K1

Escherichia coli K1 isolates synthesize a polysialic acid (polySia) capsule, are components of the adult gastrointestinal microbiota and may cause lethal bacteraemia and meningitis if acquired maternally by newborn infants. We used a neonatal rat pup K1 infection model to establish that prompt administration of a selective capsule depolymerase reverses the bacteraemic state and prevents death of almost all pups. In untreated animals, bacteria colonize the gastrointestinal tract and gain entry to the blood compartment, where they express the non-O-acetylated form of polySia. The bacteria invade the major organs of the host; histological and histochemical analysis of brain sections revealed that at least some bacteria enter the central nervous system through the blood-cerebrospinal fluid barrier at the choroid plexus prior to colonization of the meninges. Once in this location, they cease expression of polySia. The unexpected abrogation of polySia, a factor associated with the pathogenesis of meningitis and essential for transit through the blood, suggests that the neuropathogen dispenses with its protective capsule once it has colonized protected niches. Thus, systemic infections due to encapsulated pathogens may be resolved by capsule depolymerization only if the enzyme modifies the bacteria whilst they are in the blood compartment.

Meningitis in preterm neonates: importance of cerebrospinal fluid parameters

Cerebrospinal fluid parameters are of great importance in diagnosing meningitis, but normal values for preterm neonates are based on small, single-center studies. We sought to determine current values for preterm neonate cerebrospinal fluid parameters and assess the association of cerebrospinal fluid parameters with culture proven meningitis. We performed a cohort study of the first lumbar puncture from 4632 neonates < 34 weeks' gestation performed in the years 1997 to 2004 at 150 neonatal intensive care units managed by the Pediatrix Medical Group. We identified 95 cases of meningitis from the 4632 lumbar punctures. The area under the receiver operating characteristic curves for white blood cell count, glucose, and protein were 0.80, 0.63, and 0.72, respectively, for prediction of culture-proven meningitis. Cerebrospinal fluid parameters used to diagnose meningitis in the absence of dependable cerebrospinal fluid cultures are unreliable. Caution should be employed when interpreting cerebrospinal fluid parameters in the premature neonate.